9839( 9) - 10/28/03 15:05 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9839 Version: 9 Check-in Date: 28-Oct-2003 15:04:21 1.Proposal Title: Recombination Lines and Temperature Structure in Planetary Nebulae ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 12 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Dr. Donald R Garnett University of Arizona ------------------------------------------------------------------------------------ 5. Abstract A high-spatial resolution study of recombination lines (RLs) in bright compact planetary nebulae (PNs) is proposed. Many PNs show a large discrepancy between abundances derived from O II RLs and those derived from [O III]. Others show little or no discrepancy. The PNs with small discrepancies are more compact and high surface brightness. This program seeks to understand why PNs show such differences by studying the RLs at high spatial resolution in the compact PNs NGC 6572 and NGC 6790, which show no discrepancy between O II and [O III], to compare with ground- based studies of the larger PNs NGC 6153 and NGC 6720. The goal is to determine if the distribution of RL emission in NGC 6572 and NGC 6790 is more consistent with radiative recombination than in NGC 6720, where the RL emission is more centrally peaked than [O III]. This will allow us to demonstrate whether or not it is the RLs that are preferentially enhanced in the nebulae with large discrepancies. The Cat's Eye nebula NGC 6543 will also be observed, to determine if the enhanced RL emission is connected to the presence of X-ray emitting gas, as might be expected if the enhanced RLs are a result of high temperature dielectronic recombination. ------------------------------------------------------------------------------------ 9839( 9) - 10/28/03 15:05 - [ 2] Observations Description ------------------------ The targets are three high surface brightness PNs for which ground-based spectral observations are in hand. From the ground-based spectra we get average surface brightnesses in the relevant emission lines. Examination of available WFPC2 images for the targets in question show that the local surface brightness is typically within a factor two of the mean. Where appropriate we can bin to improve signal/noise. Most of the requested time will be spent in observing the C II 4267 A and O II 4661 A recombination lines with STIS/CCD using the grating setups G430M(4194) [4051-4337 A] and G430M(4706) [4563-4849 A]. Other O II RLs will also be present in the targeted spectral regions, but the two lines listed are the brightest C II and O II lines that are not blended with other lines. Short exposures with G430L at the same position will be used to obtain high spatial resolution data on [O II] 3727 A, [O III] 4959 A, and [O III] 4363 A, which will be used to derive electron temperatures (from the 4959/4363 ratio) and the ionization ratio O+/O++ across the slit. The G430M positions include relatively strong lines (H-delta and He II 4686) which will allow us to verify the photometric consistency between the medium and low-resolution spectra. The table below lists average emission line surface brightnesses in erg cm-2 s-1 arcsec-2 for the proposed targets, obtained from the ground-based spectra. For the purposes of estimating exposure times, a target signal/noise of 5-10 per spectral resolution element per spatial pixel was assumed for the 52x0.2 slit, binned 2 by 2, for the O II 4661 and C II 4267 lines in the G430M spectra, and signal/noise of 15 for [O III] 4363 in the G430L spectra. I used the STIS ETC to estimate the counts obtained for a given exposure time; I assumed an average sky background and dark (which contribute negligibly) and a conservative estimate of one-half the stellar continuum value to represent nebular continuum (it was not possible to estimate this directly from the ground-based spectra because of poor spatial resolution). I examined the computed tables of counts per pixel to determine the signal/noise in the line itself , minus the continuum, to derive the expsoure times t(exp) listed in the table. With these assumptions and surface brightnesses, we see that most of the observing time will be spent on O II 4661. C II 4267 is roughly 5 times brighter and so requires significantly less time, while the G430L observations will take only 100-400s. S(lambda) (erg cm-2 s-1 arcsec-2) Line NGC 6572 t(exp) NGC 6543 t(exp) NGC 6790 t(exp)--------------------------------------------------------- ------------------------------------------------------------------------ C II 4267 2.7e-14 600 1.0e-14 1600 0.4e-14 3000 O II 4661 0.5e-14 2400 0.2e-14 4800 0.06e-14 10600 [O III] 4363 50.e-14 100 1.8e-14 400 15.e-14 100 [O III] 4959 3000.e-14 100 210.e-14 100 430.e-14 100 H-delta 4101 140.e-14 100 23.e-14 100 17.e-14 100 H-beta 4861 720.e-14 100 93.e-14 100 91.e-14 100 Accordingly, we will need the following number of orbits for each target. NGC 6572: 1 orbit for G430M(4706) and 1 orbit for G430M(4194) + G430L. NGC 6543: 2 orbits for G430M(4706) and 1 orbit for G430M(4194) + G430L. NGC 6790: 4 orbits for G430M(4706) and 2 orbits for G430M(4194) + G430L. Target positions will be derived from the WFPC2 images; DSS images for these PNs are saturated because they are so bright, so the DSS is not optimal for determining positions. All three PNs have archived WFPC2 images, but I am requesting one orbit to obtain WFPC2 early acquisition images for NGC 6572, since in the archived images for that object the PN falls off the edge of the PC frame. I will center the STIS slit on the central star, using standard acquisition. The slit orientation is not very important, although I will attempt to optimize the orientation to 9839( 9) - 10/28/03 15:05 - [ 3] maximize the count rates. Following target acquisition I will start with the G430L observation, then switch to G430M(4194). For NGC 6752 and NGC 6543 these can be done in a single orbit. The remainder of the orbits will be used to observe with G430M(4706). Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9839( 9) - 10/28/03 15:05 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6543 ISM, PLANETARY NEBULA RA=17H 58M 33.35S +/- 0.1", J2000 V = - V = 11.0+/-0.1 DEC=66D 37' 58.66" +/- 0.1", 66.0 SURF(4267)=1.0e-14 PLATE-ID=00T0 SURF(4661)=0.2e-14 SURF(4959)=210.e-14 SURF(4861)=93e-14 Coordinate Source: HST_IMAGE 2 NGC6572 ISM, PLANETARY NEBULA RA=18H 12M 6.33S +/- 0.1", J2000 V = -8.5 V = 13.0+/-0.1 DEC=06D 51' 13.3" +/- 0.1", SURF(4267)=2.7e-14 PLATE-ID=02V7 SURF(4661)=0.5e-14 SURF(4959)=3000e-14 SURF(4861)=720e-14 Coordinate Source: GSC_SURVEY_PLATE 3 NGC6790- STAR, UNDESIGNATED RA=19H 22M 54.63S +/- 0.1", J2000 V = 13.1+/-0.4 OFFSET DEC=01D 30' 51.9" +/- 0.1", PLATE-ID=02CT Coordinate Source: GUIDE_STAR_CATALOG Comments: Target Acquisition for NGC 6790. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1954.3 -0.0018 -0.0073 0.0 4 NGC6790 ISM, PLANETARY NEBULA RA=19H 22M 56.96S +/- 0.1", J2000 V = 40.0 V = 11.0+/-0.3 DEC=01D 30' 46.4" +/- 0.1", SURF(4267)=2.8e-14 PLATE-ID=02CT SURF(4661)=0.6e-14 SURF(4959)=3200e-14 SURF(4861)=640.e-14 Coordinate Source: HST_IMAGE 5 NGC6572-STIS ISM, PLANETARY NEBULA RA=18H 12M 6.41S +/- 0.1", J2000 V = -8.5 B = 13.1+/-0.3 DEC=06D 51' 11.9" +/- 0.1", B-V = 0.1+/-0.2 PLATE-ID=02V7 Coordinate Source: HST_IMAGE 9839( 9) - 10/28/03 15:05 - [ 5] Visit: 01 Visit Priority: Visit Requirements: PCS MODE FINE On Hold Comments: Additional Comments: Early Acquisition for Visit 02 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6572 WFPC2 IMAGE PC1 F502N CR-SPLIT=NO,SUM=1X1,ATD-GAIN=7 3 90 S Sub-Exposures: ((set-exposure-properties :visit-number "01" :exposure-number 1 :ppos nil :cpos nil :copy 1 Comments: :split nil :orbit-number 1 :duration nil) (set-exposure-properties :visit-number "01" :exposure-number 1 :ppos nil :cpos nil :copy 2 :split nil :orbit-number 1 :duration nil) (set-exposure-properties :visit-number "01" :exposure-number 1 :ppos nil :cpos nil :copy 3 :split nil :orbit-number 1 :duration nil) ) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6572 WFPC2 IMAGE PC1 F656N CR-SPLIT=NO,SUM=1X1,ATD-GAIN=7 3 60 S SAME POS AS 1 Sub-Exposures: ((set-exposure-properties :visit-number "01" :exposure-number 2 :ppos Comments: nil :cpos nil :copy 1 :split nil :orbit-number 1 :duration nil) (set-exposure-properties :visit-number "01" :exposure-number 2 :ppos nil :cpos nil :copy 2 :split nil :orbit-number 1 :duration nil) (set-exposure-properties :visit-number "01" :exposure-number 2 :ppos nil :cpos nil :copy 3 :split nil :orbit-number 1 :duration nil) ) ------------------------------------------------------------------------------------------------------------------------------------ 9839( 9) - 10/28/03 15:05 - [ 6] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6572 WFPC2 IMAGE PC1 F555W CR-SPLIT=NO,SUM=1X1,ATD-GAIN=7 2 50 S SAME POS AS 1 Sub-Exposures: ((set-exposure-properties :visit-number "01" :exposure-number 3 :ppos Comments: nil :cpos nil :copy 1 :split nil :orbit-number 1 :duration nil) (set-exposure-properties :visit-number "01" :exposure-number 3 :ppos nil :cpos nil :copy 2 :split nil :orbit-number 1 :duration nil) ) ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC6572 WFPC2 IMAGE PC1 F487N CR-SPLIT=NO,SUM=1X1,ATD-GAIN=7 3 120 S SAME POS AS 1 Sub-Exposures: ((set-exposure-properties :visit-number "01" :exposure-number 4 :ppos Comments: nil :cpos nil :copy 1 :split nil :orbit-number 1 :duration nil) (set-exposure-properties :visit-number "01" :exposure-number 4 :ppos nil :cpos nil :copy 2 :split nil :orbit-number 1 :duration nil) (set-exposure-properties :visit-number "01" :exposure-number 4 :ppos nil :cpos nil :copy 3 :split nil :orbit-number 1 :duration nil) ) ------------------------------------------------------------------------------------------------------------------------------------ 9839( 9) - 10/28/03 15:05 - [ 7] Visit: 02 Visit Priority: Visit Requirements: PCS MODE FINE ORIENT 130D TO 160D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6572-STI STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1 S S CD P ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6572-STI STIS/C ACCUM 52X0.2 G430L 4300 CR-SPLIT=NO,GAIN=1,BINAXIS2=2, 3 120 S S CD BINAXIS1=2 ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6572-STI STIS/C ACCUM 52X0.2 G430M 4194 CR-SPLIT=NO,GAIN=1,BINAXIS2=2, 3 860 S SAME POS AS 2 S CD BINAXIS1=2 ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC6572-STI STIS/C ACCUM 52X0.2 G430M 4706 CR-SPLIT=NO,GAIN=1,BINAXIS2=2, 5 840 S SAME POS AS 3 S CD BINAXIS1=2 ------------------------------------------------------------------------------------------------------------------------------------ 9839( 9) - 10/28/03 15:05 - [ 8] Visit: 03 Visit Priority: Visit Requirements: ORIENT 190.0D TO 210.0D On Hold Comments: Additional Comments: ORIENTS from 205 to 210 strongly preferred if schedulable. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6543 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 0.5 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6543 STIS/C ACCUM 52X0.2 G430L 4300 CR-SPLIT=NO,GAIN=1,BINAXIS2=2, 3 150 S CD BINAXIS1=2 ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6543 STIS/C ACCUM 52X0.2 G430M 4194 CR-SPLIT=NO,GAIN=1,BINAXIS2=2, 5 960 S SAME POS AS 2 CD BINAXIS1=2 ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC6543 STIS/C ACCUM 52X0.2 G430M 4706 CR-SPLIT=NO,GAIN=1,BINAXIS2=2, 6 1560 S SAME POS AS 2 CD BINAXIS1=2 ------------------------------------------------------------------------------------------------------------------------------------ 9839( 9) - 10/28/03 15:05 - [ 9] Visit: 04 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6790-OFF STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1 S Sub-Exposures: SET CD P ((set-exposure-properties :visit-number "04" :exposure-number 1 :ppos nil :cpos nil :copy nil Comments: Acquisition using star from Guide Star :split nil :orbit-number Catalog, then blind offset to center of NGC 1 :duration nil) ) 6790 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6790 STIS/C ACCUM 52X0.2 G430L 4300 CR-SPLIT=NO,GAIN=1,BINAXIS2=2, 3 120 S Sub-Exposures: CD BINAXIS1=2 ((set-exposure-properties :visit-number "04" :exposure-number 2 :ppos nil :cpos nil :copy 1 Comments: :split nil :orbit-number 1 :duration nil) (set-exposure-properties :visit-number "04" :exposure-number 2 :ppos nil :cpos nil :copy 2 :split nil :orbit-number 1 :duration nil) (set-exposure-properties :visit-number "04" :exposure-number 2 :ppos nil :cpos nil :copy 3 :split nil :orbit-number 1 :duration nil) ) ------------------------------------------------------------------------------------------------------------------------------------ 9839( 9) - 10/28/03 15:05 - [ 10] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6790 STIS/C ACCUM 52X0.2 G430M 4194 CR-SPLIT=NO,GAIN=1,BINAXIS2=2, 3 860 S SAME POS AS 2 CD BINAXIS1=2 Sub-Exposures: ((set-exposure-properties :visit-number "04" :exposure-number 3 :ppos Comments: nil :cpos nil :copy 1 :split nil :orbit-number 1 :duration nil) (set-exposure-properties :visit-number "04" :exposure-number 3 :ppos nil :cpos nil :copy 2 :split nil :orbit-number 1 :duration nil) (set-exposure-properties :visit-number "04" :exposure-number 3 :ppos nil :cpos nil :copy 3 :split nil :orbit-number 2 :duration nil) ) ------------------------------------------------------------------------------------------------------------------------------------ 9839( 9) - 10/28/03 15:05 - [ 11] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC6790 STIS/C ACCUM 52X0.2 G430M 4706 CR-SPLIT=NO,GAIN=1,BINAXIS2=2, 5 840 S SAME POS AS 2 CD BINAXIS1=2 Sub-Exposures: ((set-exposure-properties :visit-number "04" :exposure-number 4 :ppos Comments: nil :cpos nil :copy 1 :split nil :orbit-number 2 :duration nil) (set-exposure-properties :visit-number "04" :exposure-number 4 :ppos nil :cpos nil :copy 2 :split nil :orbit-number 2 :duration nil) (set-exposure-properties :visit-number "04" :exposure-number 4 :ppos nil :cpos nil :copy 3 :split nil :orbit-number 3 :duration nil) (set-exposure-properties :visit-number "04" :exposure-number 4 :ppos nil :cpos nil :copy 4 :split nil :orbit-number 3 :duration nil) (set-exposure-properties :visit-number "04" :exposure-number 4 :ppos nil :cpos nil :copy 5 :split nil :orbit-number 3 :duration nil) ) ------------------------------------------------------------------------------------------------------------------------------------ 9839( 9) - 10/28/03 15:05 - [ 12] Summary Form for Proposal 9839 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PC1 F28X50LP 52X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO SUM=1X1 ATD-GAIN=7 ACQTYPE=POINT BINAXIS1=2 BINAXIS2=2 GAIN=1 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE FINE Sub-Exposures ((set-exposure-properties visit-number "01" exposure-number 1 ppos nil cpos nil copy 1 split nil orbit-number 1 duration nil) (set-exposure-properties visit-number "01" exposure-number 1 ppos nil cpos nil copy 2 split nil orbit-number 1 duration nil) (set-exposure-properties visit-number "01" exposure-number 1 ppos nil cpos nil copy 3 split nil orbit-number 1 duration nil) ) SAME POS AS 1 Sub-Exposures ((set-exposure-properties visit-number "01" exposure-number 2 ppos nil cpos nil copy 1 split nil orbit-number 1 duration nil) (set-exposure-properties visit-number "01" exposure-number 2 ppos nil cpos nil copy 2 split nil orbit-number 1 duration nil) (set-exposure-properties visit-number "01" exposure-number 2 ppos nil cpos nil copy 3 split nil orbit-number 1 duration nil) ) SAME POS AS 1 Sub-Exposures ((set-exposure-properties visit-number "01" exposure-number 3 ppos nil cpos nil copy 1 split nil orbit-number 1 duration nil) (set-exposure-properties visit-number "01" exposure-number 3 ppos nil cpos nil copy 2 split nil orbit-number 1 duration nil) ) SAME POS AS 1 Sub-Exposures ((set-exposure-properties visit-number "01" exposure-number 4 ppos nil cpos nil copy 1 split nil orbit-number 1 duration nil) (set-exposure-properties visit-number "01" exposure-number 4 ppos nil cpos nil copy 2 split nil orbit-number 1 duration nil) (set-exposure-properties visit-number "01" exposure-number 4 ppos nil cpos nil copy 3 split nil orbit-number 1 duration nil) ) PCS MODE FINE ORIENT 130D TO 160D SAME POS AS 2 SAME POS AS 3 ORIENT 190.0D TO 210.0D Sub-Exposures ((set-exposure-properties visit-number "04" exposure-number 1 ppos nil cpos nil copy nil split nil orbit-number 1 duration nil) ) Sub-Exposures ((set-exposure-properties visit-number "04" exposure-number 2 ppos nil cpos nil copy 1 split nil orbit-number 1 duration nil) (set-exposure-properties visit-number "04" exposure-number 2 ppos nil cpos nil copy 2 split nil orbit-number 1 duration nil) (set-exposure-properties visit-number "04" exposure-number 2 ppos nil cpos nil copy 3 split nil orbit-number 1 duration nil) ) SAME POS AS 2 Sub-Exposures ((set-exposure-properties visit-number "04" exposure-number 3 ppos nil cpos nil copy 1 split nil orbit-number 1 duration nil) (set-exposure-properties visit-number "04" exposure-number 3 ppos nil cpos nil copy 2 split nil orbit-number 1 duration nil) (set-exposure-properties visit-number "04" exposure-number 3 ppos nil cpos nil copy 3 split nil orbit-number 2 duration nil) ) SAME POS AS 2 Sub-Exposures ((set-exposure-properties visit-number "04" exposure-number 4 ppos nil cpos nil copy 1 split nil orbit-number 2 duration nil) (set-exposure-properties visit-number "04" exposure-number 4 ppos nil cpos nil copy 2 split nil orbit-number 2 duration nil) (set-exposure-properties visit-number "04" exposure-number 4 ppos nil cpos nil copy 3 split nil orbit-number 3 duration nil) (set-exposure-properties visit-number "04" exposure-number 4 ppos nil cpos nil copy 4 split nil orbit-number 3 duration nil) (set-exposure-properties visit-number "04" exposure-number 4 ppos nil cpos nil copy 5 split nil orbit-number 3 duration nil) ) ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F502N F656N F555W F487N MIRROR G430L G430M ------------------------------------------------------------------------------------------------------------------------------------ 9839( 9) - 10/28/03 15:05 - [ 13] Summary Form for Proposal 9839 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC6572 NGC6572-STIS NGC6543 NGC6790-OFFSET NGC6790 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 4300 4194 4706 ------------------------------------------------------------------------------------------------------------------------------------